var b64map="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var b64pad="=";

function hex2b64(h) {
    var i;
    var c;
    var ret = "";
    for(i = 0; i+3 <= h.length; i+=3) {
        c = parseInt(h.substring(i,i+3),16);
        ret += b64map.charAt(c >> 6) + b64map.charAt(c & 63);
    }
    if(i+1 == h.length) {
        c = parseInt(h.substring(i,i+1),16);
        ret += b64map.charAt(c << 2);
    }
    else if(i+2 == h.length) {
        c = parseInt(h.substring(i,i+2),16);
        ret += b64map.charAt(c >> 2) + b64map.charAt((c & 3) << 4);
    }
    while((ret.length & 3) > 0) ret += b64pad;
    return ret;
}

// convert a base64 string to hex
function b64tohex(s) {
    var ret = ""
    var i;
    var k = 0; // b64 state, 0-3
    var slop;
    for(i = 0; i < s.length; ++i) {
        if(s.charAt(i) == b64pad) break;
        v = b64map.indexOf(s.charAt(i));
        if(v < 0) continue;
        if(k == 0) {
            ret += int2char(v >> 2);
            slop = v & 3;
            k = 1;
        }
        else if(k == 1) {
            ret += int2char((slop << 2) | (v >> 4));
            slop = v & 0xf;
            k = 2;
        }
        else if(k == 2) {
            ret += int2char(slop);
            ret += int2char(v >> 2);
            slop = v & 3;
            k = 3;
        }
        else {
            ret += int2char((slop << 2) | (v >> 4));
            ret += int2char(v & 0xf);
            k = 0;
        }
    }
    if(k == 1)
        ret += int2char(slop << 2);
    return ret;
}

// convert a base64 string to a byte/number array
function b64toBA(s) {
    //piggyback on b64tohex for now, optimize later
    var h = b64tohex(s);
    var i;
    var a = new Array();
    for(i = 0; 2*i < h.length; ++i) {
        a[i] = parseInt(h.substring(2*i,2*i+2),16);
    }
    return a;
}